The results of radiated performance tests, including sensitivity tests, of a wireless receiver in an anechoic chamber are strongly dependent on the antenna pattern. The antenna pattern can be altered if additional wires or cables are attached for test purposes but which do not exist under the normal operating conditions for the device. By attaching wires or cables for test purposes, the accuracy of the test results are affected.
Inaccuracies are also further caused by signals travelling along the wires or cables attached for test purposes. These signals generate interference that is radiated into the space around the receiver or are coupled through surrounding circuitry, and this interference or coupling may also affect the test accuracy.
If wireless means such as Bluetooth or IrDa are used instead of cable, the spurious emissions from a Bluetooth or IrDa transceiver may also cause interference that is radiated into the space around the receiver, affecting test accuracy. It is therefore desirable not to use wireless communications other than the test signal during testing.
In wireless devices that normally operate in two directions simultaneously, i.e. transmitting while receiving (either simultaneously in time or being time multiplexed), the transmitting channel can be used as a means to report the receiving performance values. These receiving performance values include bit error rate, frame error rate, block error rate, detection rate, or misdetection rate, false alarm rate, etc. In a device which operates in two directions, no attached wire or cable is necessary. Instead, such devices loop back data that is received or send messages in the transmit direction that report performance values.
For wireless devices that only operate in one direction at a time, or for testing operating modes that only use one direction, or for the type of test equipment that does not have the capability to obtain reported test messages over the air, or for prototypes that have limited test support functionality, other means of retrieving performance data from within the device are needed.
A current method of testing devices includes attaching a cable between the device under test and a computer through a serial interface. Test scripts, which are prepared in advance of the tests, are initiated from the computer and the contents are sent through the data cable to the device. Software on the device under test has the capability of accepting commands received through the data cable. The software further interprets the commands and acts according to these commands. The results of the actions are logged and these logs are sent back to the computer using the same data cable. These log results are further interpreted to obtain the results of the test. Since the data cable is attached to the device all the time during the test to maintain the communication between the device under test and the computer, the results of the test are tainted by the use of the cable.